Antivibration mount for airplane instruments



| NvENT'oR B. G. CARLSON Filed May 24, 1935 ANTIVIBRATION MOUNT FOR AIRPLANE INSTRUMENTS Nov. 3, 1936.

' automatic pilot Patented Nav. 3,1936

Nlren sTA'rs" new o.. ceram, generosas. afin' Spe Gyroscope Company, llnc., Eroc,

Mill., a corporation oi Application May 2d, ll

` (ci. ala-ssa) o ci.

This invention relates, generally, to means for :supporting automatic pilots and other sensitive devices within aircraft so that such devices are protected against engine vibrations, shoclr .fand

ii -bther disturbing forces, and the invention has reference, more particularly, to novel shoclr absorbing supports to be used lor this purpose.

The principal object oi the present invention is to provide novel shock absorbing supports for lil automatic pilots and other devices having resiliently yieldabie means for carrying the weight oi the device, whereby vibrations and shocks are cushioned and are either not transmitted to the supported device or else transmitted in a gradual ld manner so that no injury can result to such supported device, the said shock absorbing supports having energyoonsuming means for dissipating the energy transmitted to the resiliently yieldable carrying means byvibrations and shocks. m i Other objects and adva tages will become apparent from the specica ion, taken in connection with the accompanyingy drawing wherein one embodiment ol the invention is illustrated ln the drawing,

25 Fig. l is a view in front elevation, with parts broken away or omitted; illustrating an automatic pilotsupported upon a base plate by the novel shock absorbing supports oi this invention.

Fig. 2 is a reduced plan view ol thebase plate ma oi Fig. l, having the vnovel shock absorbing supports olthis inventionthereon. I l llig. 3 is an enlarged fragmentary sectional view ten along line' oi Fig.l2 and illustrating one ci the vnovel shochl Iabsorbingsummits in 3g section, and Q Fig. 4 is a view :i` ai .to Fig. d, but illustrates y the action ol the shoe absorbing support as the result oi `a iorce acting inthe direction oi the s i now to the said draw, the reier ence numeral vi designates `the iront panel oi ch as that disclosed in Patent No. 1,992,910, the said automatic pilot having a directional gyroscope i and an .artificial horizon aa unit t together with associated apparatus mount- Ved behind the. panel i. 'The automatic pilot^is supportedby means of the novel shock absorbing supports t oi this invention upon a base plate l that is dxedly attached to the traine oi the airdil sa v'crafty the said base plate .beingK illustrated as carrying control knobs 5 for valves serving to supply oil .through flexible tubes` 'i fi to the various units oi the automatic pilot. Ai-

though the novel shock' absorbing supports arev 5s illustrated supporting an'automatfc Pilot, it is Ncw'horh v 935, nel lilo. ilhld to lbe 'understood that-the same may be used for supporting other devices to be protected against vibration and shocks.

According to the preferred construction, 'each of the shock" absorbing supports t comprises a shallow cylindrical casing t open at its top and having a central circular aperture t in its bottom it. Casing t has an' outwardly directed substantially square ange. .il at its top, which ange is provided with vertical apertures at its corners ior receiving screws ii that extend through the nangel i i and are threaded into bosses ld provided on ibasel plate t, thereby rigidly supporting the casing d upon the base plate il.

A cylindrical housing member it extends ver- `ld tically upwardly through casing aperture d and -has an annular, horizontal ilange it projecting outwardly from its upper portion. The periphf eral portion ol ange it rests and is supported upon an annular ring member iii that is set into and flxedly retained within an' annular groove il provided in the casing nange il The ring member it is preferably made of hardened material, such as hardened steel, while the flange it is preferably made oi a sorter material, sueh'as 25 brass or bronze, the flange it being free to slide horizontally over the supporting ring member it, as will further appear. Housing member it has a lower reduced po tion it that isxternally threaded lor receiving a nut it. d coil compression spring it 'surf rounds-the lower part of housing id and bears 'at its lower end upon nut it and at its upper end against a washer il that hasa sliding t on housing it. Washer it is thus pressed upwardly by spring it against a ring member il that is lar to ring member. it. Ring member il is preierably de oi hardened material and is' hxedly retained in van annular groove li provided Iin the bottom it of casing t, while washer il M, is preferably made oi a.. somewhat softer material and is'free/to slide horizontally with respect oo ring memberdl, aswill urther appear. 'y

AWith the cylindrical housing member it thus assembled upon the `casing i, there is provided an annular space it within casing il and surrounding housing 'member it. Aspral centering spring i6 is contained within space it and bears -at its outer endl portion upon the inner wall of leasing iland at its inner end portion upon'the ga vouter surface of Vhousing member-lt, thereby tending by its tensionto retain housing Vmember i4 centrally or casing t so that the vertical axes of housing member lt and casing d substantially coincide. A cylindrical plunger 2l entends down# sa housing member .I 4 and is vertically slidable within this housing member. Plunger 21 has a reduced lower portion 28 that extends downwardlyv within housing member .|4, thereby providing an annular chamber 24 within this housing member. Portion 28 extends through a central slide bearing aperture 29 provided in the reduced portion I8 of member I4.

A coil compression spring 30 surrounds the portion 28 'of plunger 21 within chamber 24 and bears at its lower end upon the lower portion I8 of housing member I4 and at`its upper end upon the under surface of the enlarged upper portion o'f plunger 21, thereby urging this plunger upwardly. A headed screw 3| is threaded upwardly into the lower end of plunger 21, the head of which screw serves, by engaging the lower end of housing member I4, to limit the upward movement of plunger 21 under the action `of spring` 30. The top of plunger 21 is provided with an outwardly projecting annular flange .32 which, by engaging the upper end of housing sideration just serves to compress-spring 30 sufcintly so that the flange 32 and the head of screw 3| are spaced substantially equal distances; respectively, labove and below the top and bottom of housing member I4, as shownln Fig. 3. The chamber 24 is' connected to the interior of housing member I4 by a small air vent or aperture 35 extending through the side wall of housing member I4.

In use, with the automatic pilot resting upon the shock absorbing supports 6, the parts of each of these supports are positioned about as shown in Fig. 3. The automatic pilot or other supported device possesses inertia, owing to its weight, and hence tends to remain in a state of and since they are substantially non energy consuming, they would tend to transmit a reduced amplitude of the vibrations to the supported automatic pilot, and thus set the later in motion, but for the snubbing or frictional energy consuming action of air moving in and out of air vent 35 and the frictional action of flange I5 and washer 2| sliding transversely upon ring members I6 and 22, respectively. This will be apparent when it is noted that as casing 8, flxedly supported upon the aircraft frame, moves verti` cally under the action of a disturbing force, it

correspondingly moves the housing member I4 vertically, whereby this housing member moves -with respect to theA relatively stationary plunger 21 connected to the automatic pilot, so that spring 30 is deflected and the volume of annular chamber 24 surrounding plunger 21 within housing member I4 changes, thereby causing air to be Vwardly into the open upper end of the hollow either forced out .through the small orice 35 or drawn in therethrough, depending upon whether housing member I4 moves upwardly or downwardly with respect to plunger 21. The frictional energy consuming action of the air in flowing through orifice 35 serves as acheck to snub the rebound of spring 30 in both directions and hence prevents the transmission of motion to the automatic pilot. Likewise, transverse movements of casing 8 with respect to housing member I4, due to a horizontally acting disturbing force or force component, causes the deflection of spiral spring 26 while-housing member I4 remains substantially'stationary, the' frictional resistance of ange I5 and washer 2| in sliding over annular ring members I6 and 22 serving to snub the rebound of spring 26 in both directions.

Thus, engine vibrations and other disturbing forces of relatively short amplitude and time duration are effectively prevented from being transmitted to the automatic pilot or other supported device, and all sudden shocks, even though of relatively long time duration, are considerably cushioned by the action of the novel shock absorbing supports of this invention, whereby the accuracy and dependability of the automatic pilot areV great-ly enhanced in use,.thereby increasing the eflciency thereof as well as protecting the same from injury.

As many changes could be made in the above A construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all'matter contained in the abovel description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. A shock labsorbing support for automatic pilots and other devices carried by aircraft, comprising a casing attached to the aircraft, a housing member frictionally supported directly upon said casing for limited transverse movement with respect to the latter, a plunger member connected for supporting the automatic pilot, said plunger member projecting into said housing member for Vlimited vertical movement therein, resilientmeans interposed between said housing member and said casing, the frictional support of said housing memberupon saidvcasing serving to check said resilient meansz and additional resilient means between said housing member and said plunger member, whereby said plunger member and the connected automatic pilot are cushioned against disturbing forces applied to said casing, and means for snubbing said additional resilient means. I

2. A shock absorbing support for automatic pilots and other devices carried by aircraft, comprising a casing' attached to the aircraft, a housing member supported upon said casing for limited transverse movement with respect to the latter,

. spring means interposed between said casing and said housing member, said-casing and said housing member having cooperable friction surfaces for snubbing said spring means, a plunger member connected for supporting the automatic pilot, said plunger member projecting into said housing member for limited vertical sliding movement therein, and additional spring means interposed between said housing member and sa'id plunger member, said housing member and said plunger `member being so constructed and arranged, whereby limited ingress and egress of air from' to said casing are cushioned before reaching said plunger and its connected automatic pilot.

`3. A shock absorbing support for automatic pilots and other devices carried by aircraft, comprising a casing attached to the aircraft, a housing member frlctionally supported directly upon said casing for limited transverse movement with respect to the latter, a plunger member connected for supporting the automatic pilot, said plunger member projecting into said housing member for limited vertical movement therein, horizontally acting spring means interposed between said casing and said housing member, the frictional support of said housing member on saidcasing serving to snub said horizontally acting spring means, vertically acting spring means 'interposed between said housing member and said plunger member, said casing and said housing member being constructed and arranged to provide a dash pot4 action for snubbing said vertically acting spring means in both directions,

whereby the automatic pilot is substantially unaffected by engine vibrations and other disturbing forces.

4. A shock absorbing support for automatic pilots and other .devices carried by aircraft, comprising a. vertically extending substantially cylindrical casing, a vertical housing member eX- tending into said casing and supported thereupon for limited transverse movement, a spiral spring within said casing and engaging said housing member for holding the latter substantially centrally of said casing, a plunger extending downwardly into said housing member for limited vertical movement therein, and a coil supporting spring interposed between said plunger and said housing member, said housing member having an 'orice in the wall thereof, whereby relative vertical movement of said housing member with respect to said plunger, due to deections of said coil spring, will cause air to flow through said orifice, thereby checking the motion of said coil spring.

5. A shock absorbing support for automatic pilots and other devices carried by aircraft, com-V prising 'a vertically extending substantially cylindrical casing, a vertical housing member extending into said casing and supported thereupon for limited transverse movement, a horiy zontally disposed spiral spring confined within said casing and engaging said housing member for yieldably holding the latter substantially centrally of said casing,fthe frictional engagement of said housing member upon said casing serving to`snubdeecting movements of said spring, a ,verticalplunger extending into said housing member for limited vertical movement therein,

a coil compression spring interposed between said plunger and said housing member for supporting the-former upon the latter, said housing member and plunger assembly having a restricted air opening to effect the snubbing of said coil spring inuse.

6. A shock absorbing support for automatic pilots and other devices carried by aircraft, comprising a vertical, substantially cylindrical casing open atits top and attached to the aircraft, a substantially cylindrical housing member extending vertically downwardly through the open top of said casing and having a flange resting on the top of said casing for supporting said housing member on saidv casing while allowing limited transverse movement ofv said housing member with respect to said casing, ahorizontally disposed spiral spring confined within said ycasing and engaging said housing member for 

